So, basically, a channel strip may be what you are looking for? In that price range there are a few decent contenders, but as mentioned above, depending on how good the PA console is, that may be all that is needed beyond a good DI to get you in there.

Used is not necessarily better, but you can potentially get more for your money. Of course, there is the potential risk of issues (although new stuff goes bad, too) with no manufacturers warranty to help in that situation.

What is it that the church is looking for in having a separate, dedicated preamp for the bass as opposed to the channel controls of the PA board? Can you give us more details as to why this is needed in the first place?

I agree with the Tech 21 Sansamp suggestion as I own one but I also bought a David Eden World Tour DI (WTDI) pedal online from Rock Block Guitars in Nashville for a similar price: rockblockguitars.net/

I think that the WTDI is an absolutely superb preamp and is basically a replica of the big rack mount David Eden WT in a very compact box. Have a look at that one as well.

I agree with the Tech 21 Sansamp suggestion as I own one but I also bought a David Eden World Tour DI (WTDI) pedal online from Rock Block Guitars in Nashville for a similar price: rockblockguitars.net/

I think that the WTDI is an absolutely superb preamp and is basically a replica of the big rack mount David Eden WT in a very compact box. Have a look at that one as well.